Air distributor for obtaining uniform head-tape contact in magnetic tape transport

ABSTRACT

The specification discloses an air distributor for evenly distributing the flow of air against the width of a magnetic tape to maintain the tape along its entire width adjacent a read/write headstack of a tape transport to enhance the read/write reliability of the transport. The air distributor comprises structure having a plurality of passageways arranged in at least one array along a given dimension of the structure. The passageways increase in size outward from the center of the array. In the embodiment disclosed, the distributor has two arrays of passageways formed in opposite edges of the structure. The distributor is supported in the transport in a manner to locate the arrays substantially perpendicular to the direction of travel of the tape and the passageways perpendicular to the plane of the tape.

United States Patent Rousso, Jr. et al.

[ 51 July 18, 1972 AIR DISTRIBUTOR FOR OBTAINING UNIFORM HEAD-TAPE CONTACT IN MAGNETIC TAPE TRANSPORT Jack J. Rousso, Jr.; George N. Willman, both of Dallas, Tex.

Mobil Oil Corporation July 14, 1970 Inventors:

Assignee:

Filed:

Appl. No.:

References Cited UNITED STATES PATENTS Edstrom 15/416 Goehle .l79/l00.2 P Timares et a]. ..226/97 AIR DISTRIBUTORS SURFACE AIR DISTRIBUTORS INSERTED Primary ExaminerBemard Konick Assistant Examiner-Jay P. Lucas Anorney-William J. Scherback, Frederick E. Dumoulin, Arthur F. Zobal, Andrew L. Gaboriault and Sidney A. Johnson [5 7] ABSTRACT The specification discloses an air distributor for evenly distributing the flow of air against the width of a magnetic tape to maintain the tape along its entire width adjacent a read/write headstack of a tape transport to enhance the read/write reliability of the transport. The air distributor comprises structure having a plurality of passageways arranged in at least one array along a given dimension of the structure. The passageways increase in size outward from the center of the array, In the embodiment disclosed, the distributor has two arrays of passageways formed in opposite edges of the structure. The distributor is supported in the transport in a manner to locate the arrays substantially perpendicular to the direction of travel of the tape and the passageways perpendicular to the plane of the tape.

5 Claim, 9 Drawing Figures DISTRIBUTOR SUPPORTS PATENTEUJULIBIQYZ 3:6?8216 SHEET 1 [IF 4 I2 TAKE-UP SUPPLY REEL REEL 17 L ,---I6 TAPE TAPE IDLER ARM nr1\\ mLER ARM 15 \30 READ/ WRITE PRESSURE PAD HEAD UNIT TAPE LOAD AND UNLOAD MECHANICS I3b :0 I30 REEL REEL DRIVE DRIVE READ HEADS IDLER x$k CAPSTAN IDLER ARM ARM 4, :9 4

0 TACHOMETER 30 TACHOMETER PRESSURE PAD AIR LIGHT SUPPLY LIGHT souRcEs souRcEs 23 22 LOOP'T /[D [3 SENS'NG JACK J. ROUSSO,JR. PHOTOCELLS GEORGE N. WILLMAN FIG. 2 INVENTORS \VACUUM/ STORAGE BY 20b COLUMNS' 20a ML EY'W TAPE PATH THROUGH TAPE UNIT ATTORNEY PAIENIED JULI 8 I972 3.678.216

SHEET 2 or 4 SURFACE AIR SUPPLY ORIGINAL PRESSURE PAD FIG. 4

JACK J. ROUSSO, JR.

GEORGE N. WILLMAN INVENTORS MJ W ATTORNEY PATENTED UH IQH! $3 678,216

SHEET 3 OF 4 TAPE SURFACE DISTRIBUTOR SUPPORTS SURFACE AIR SUPPLY JACK J. ROUSSO, JR.

GEORGE N. WILLMAN PRESSURE PAD WITH INVENTORS AIR DISTRIBUTORS INSERTED ATTORNEY PATENTEU JUL 1 8 I972 SHEET Q 0? 4 mmO 1m mmo JACK J ROUSSO,JR GEORGE N. WILLMAN INVENTORS m at ATTORNEY AIR DISTRIBUTOR FOR OBTAINING UNIFORM I-IEAD- TAPE CONTACT IN MAGNETIC TAPE TRANSPORT BACKGROUND OF THE INVENTION In the 627 Tape Transport used with Control Data Corporations 3000 or 6000 -series digital computers, the contact angle between the tape and the read/write headstack is essentially zero degrees. In this tape transport, separate headstacks are provided for read and for write purposes. A pneumatic pressure pad having a single air passageway of air slot for each headstack is employed to blow a jet of air (about 12 psi) against the opposite side of the tape as it passes under each headstack to provide head-tape contact.

It has been found that this arrangement had disadvantages in that the air slot provided for each headstack directs maximum pressure to the center of the tape rather than against the total tape surface width. This has resulted in insufiicient headtape contact along the edges of the tape to reliably read or write data from or onto the outer tracks of worn tape or tape that has suffered minor edge damage.

In the seismic industry the seismic field recording systems currently in use (especially systems which record on l-inch tape) record detected seismic data on the inner tracks and the sample rate clock (timing word) and part of the seismic record identification number on the outer tracks. If the outer tracks cannot be read, the seismic data read from the inner tracks will be undistinguishable and hence unless.

SUMMARY OF THE INVENTION In accordance with the present invention, an air distributor is provided to enhance the read/write reliability of a tape transport system. The air distributor comprises structure having a plurality of passageways arranged in at least one array along a predetermined dimension of the structure. In the embodiment disclosed, the passageways increase in size outward from the center of the array. In the transport system, the distributor is supported in an air flow path in a manner to locate the array of passageways substantially perpendicular to the direction of travel of the tape. The flow of the air from the flow path is directed by way of the passageways onto the sur face of the tape, thereby maintaining the tape along its entire width adjacent the head means. This provides for a uniform head-tape contact along the width of the tape, thereby enhancing the read/write reliability of the system.

In a further aspect, the air distributor has two arrays of passageways formed in opposite edges of the structure. The passageways extend perpendicular to the plane of the tape when the distributor is supported in the transport system whereby air is directed through each passageway substantially perpendicular to the surface of the tape.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a portion of a tape transport used with a digital computer for reading and writing data from and onto magnetic tape;

FIG. 2 is a further illustration of the tape transport showing more detail;

FIG. 3 illustrates a pneumatic pressure pad originally employed for maintaining the magnetic tape adjacent the read/write heads of the tape transport;

FIG. 4 is an end view of the pressure pad, also showing the read headstack;

FIG. 5 is a top view of the original pressure pad;

FIG. 6 illustrates the pneumatic pressure pad with air distributors employed for maintaining uniform head-tape contact;

FIGS. 7 and 8 are enlarged drawings of the top and side views of the air distributor; and

FIG. 9 illustrates in more detail the manner in which slots in the pressure pad were enlarged and an air distributor supported in one of the slots.

DESCRIPTION OF TAPE TRANSPORT Referring to FIGS. 1 and 2, a tape transport is illustrated at 10. This particular tape transport is identified as the 627 Tape Transport manufactured by Control Data Corporation. It comprises supply and tape take-up reels 11 and 12 and reel drives 13a and 13b for moving magnetic tape 14 relative to a read/write head unit 15 (FIG. 1). Tape tension and control mechanisms are provided and comprise tape idler arms 16 and 17, capstans l8 and 19, vacuum storage columns 20a and 20b, light sources 22 and 23, and loop sensing photocells 24 and 25.

The read/write head unit 15 comprises a stack of read heads 15a and a stack of write heads 15b. In a tape transport employing l-inch tape, the read headstack and the write headstack each comprises 21 heads coupled together for reading and writing, respectively, data onto and from each of the 21 tracks of the l-inch tape. Each headstack has a total width of about 1 inch.

In the 627 Tape Tramports purchmed from CDC, the contact angle between the tape and read/write headstack is essentially zero degrees as mentioned above. This s desirable for rapid tape movement. A pneumatic presure pad 30 is provided for nmintaining the tape 14 adjacent the heads of the read/write head unit.

Referring to FIG. 3, the pneumatic pressure pad 30 comprises a T-shaped metal member having a top surface 31 over which the tape 14 is moved. FIG. 4 illustrates an end view of the pressure pad 30 with the tape 14 located above the top surface 31 and also illustrating the read headstack 15a positioned above the tape 14. Air is applied to the bottom of the tape from points below the read headstack and write headstack to maintain the tape adjacent these headstacks. The air is obtained from an air supply 32 (FIG. 3) and applied to the tape by way of a flow path comprising tape 33, tube 34, and slots 35 and 36. Tube 34 is inserted into an aperture drilled into the pad 30 below the surface 31. Its opposite ends are closed; however, it has two apertures 37 and 38 (See also FIG. 5) machined or formed intermediate its ends below the center of the read headstack and below the center of the write headstack, respectively. Machined or formed into the pressure pad 30 are the two slots 35 and 36 which extend from apertures 37 and 38, respectively. Air injected into tube 34 thus flows through aperture 37 and slot 35 onto the tape and through aperture 38 and slot 36 onto the tape to maintain the tape adjacent the read headstack and adjacent the write headstack, respectively. It has been found, however, that the air blown through the slots 35 and 36 is directed primarily to the center of the tape, thus afiecting the read/write reliability of the system. The adverse effect is greater in reading l-inch tape than in reading one-half-inch tape. In the past, failure to read a record on the tape would require us to terminate computer processing operations; read the tape on another transport system employing a wrapped-head system (where tension is maintained on the tape at the location of the read/write heads); copy the data onto a new tape; and then read the data from the new tape in the 627 Transport system. This operation is time consuming and hence costly.

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 6, the read/write reliability of the system has been enhanced in accordance with the present invention by forming air distributors 50 and inserting the distributors into the slots 35 and 36 which were enlarged to accommodate the distributors. As can be seen more clearly in FIGS. 7 and 8, each distributor 50 is formed of an elongated metal member having at least one array of passageways formed therethrough. In the embodiment disclosed, two arrays of passageways or slots were formed in opposite edges of the member. In FIG. 7 the passageways of each array are identified as A -A,. The passageways or slots A -A, increase in size from the center of each array outward. The dimensions of the passageways of the distributors built are set forth in inches in FIGS. 7 and 8.

Each slot 35 and 36 was enlarged by machining out its curved bottom illustrated by the dotted line 51 in FIG. 9. The resulting slots formed each have a flat bottom surface identified at 52. Metal was left at the lower comers at 53 and 54 to form two supporting shoulders. The air distributors then were inserted into the enlarged slots 35 and 36 with the shoulders 53 and 54 supporting the air distributors above the bottom of the slots. A distributor supported in an enlarged slot is illustrated at 50 in FIG. 9. The vertical scale in FIG. 9 is different from that of FIG. 8. When the distributor is supported in the slot as shown in FIG. 9, its top surface is in the plane of the top surface 31 of the pressure pad 30. Air which flows through the tube 34 flows into the modified slots 35 and 36 below the air distributors and then through the passageways of the distributors onto the tape. Since air is blown into the slots from the small tube apertures 37 and 38, pressure is greatest in the immediate vicinity of the apertures 37 and 38. By providing smaller passageways in the center of the distributors above the apertures 37 and 38 and which increase in size outward from the center of the distributors, the flow of air pressure is evenly distributed against the full width of the tape surface. Moreover, the passageways A -A extend perpendicular to the top surface of the distributors and hence perpendicular to the plane of the tape when the distributors are inserted into the pad 30. With this arrangement, air is directed not only against the full width of the tape surface, but in a direction perpendicular to the plane of the tape.

Tests were conducted with the air distributors in reading a tape having severe damage on the edge of the tape assigned as track 21. A 30-40 percent increase in signal amplitude was observed in reading a 32-KHz signal that was recorded on the same transport. A 40 percent increase in signal amplitude was observed in reading a 32-Kl-Iz signal that was recorded on another system. A 40-50 percent increase was observed in the ability to detect the location of known discrete records prerecorded by another system. This latter test was made on three different 627 Tape Transports and the results compared to the records as read with the use of the original pressure pad in each unit.

The distributors not only enhance the read/write reliability of the 627 Tape Transport unit, but are also made cheaply, easily installed, and require no precise alignment.

What is claimed is: 1. In a magnetic tape transport system for recording and reproducing data onto and from magnetic tape of a predetermined width comprising:

head means for recording and detecting data onto and from a magnetizable surface on one side of said tape,

means for moving said magnetic tape relative to and adjacent said head means to allow recording and detection to be carried out, and

means for applying air, by way of a flow path, to the side of said tape opposite said magnetizable surface to maintain said tape adjacent said head means while recording and detection are carried out,

the combination therewith of:

air distributor means for evenly distributing the air along the width of said tape to maintain said tape along its entire width adjacent said head means,

said air distributor means comprising structure having a plurality of passageways arranged in at least one array along a predetermined dimension of said structure, and

means for supporting said structure in said flow path to locate said array of passageways substantially perpendicular to the direction of travel of said tape,

said passageways increasing in cross sectional area toward the edges of said tape outward from the point of greatest air pressure within said How path.

2. The combination of claim 1 wherein:

said structure has a surface substantially parallel to the plane of said tape when supported in said system,

said passageways extending in a direction perpendicular to said surface of said structure whereby air is directed through each passageway substantially perpendicular to the surface of said tape. 3. An air distributor means for use in a magnetic tape transport system employed for recording and reproducing data onto and from magnetic tape of a predetermined width, said air distributor means comprising:

structure having a plurality of passageways arranged in at least one array along a predetemrined dimension of said structure for directing air from a flow path to a surface of the magnetic tape by way of said passageways, said passageways increasing in cross sectional area toward the edges of said tape outward from the point of greatest air pressure within said flow path. 4. The air distributor of claim 3 wherein: said structure has a surface which is substantially parallel to the plane of said tape when supported in said tape transport system, said passageways extending in a direction perpendicular to said surface of said structure whereby air is directed through each passageway substantially perpendicular to the surface of the tape. 5. The air distributor of claim 4 wherein: said structure has two arrays of said passageways formed therethrough and parallel to each other, said passageways of each array increasing in size outward from the point of greatest air pressure within said flow path, and said passageways of each array being formed in opposite edges of said structure. 

1. In a magnetic tape transport system for recording and reproducing data onto and from magnetic tape of a predetermined width comprising: head means for recording and detecting data onto and from a magnetizable surface on one side of said tape, means for moving said magnetic tape relative to and adjacent said head means to allow recording and detection to be carried out, and means for applying air, by way of a flow path, to the side of said tape opposite said magnetizable surface to maintain said tape adjacent said head means while recording and detection are carried out, the combination therewith of: air distributor means for evenly distributing the air along the width of said tape to maintain said tape along its entire width adjacent said head means, said air distributor means comprising structure having a plurality of passageways arranged in at least one array along a predetermined dimension of said structure, and means for supporting said structure in said flow path to locate said array of passageways substantially perpendicular to the direction of travel of said tape, said passageways increasing in cross sectional area toward the edges of said tape outward from the point of greatest air pressure within said flow path.
 2. The combination of claim 1 wherein: said structure has a surface substantially parallel to the plane of said tape when supported in said system, said passageways extending in a direction perpendicular to said surface of said structure whereby air is directed through each passageway substantially perpendicular to the surface of said tape.
 3. An air distributor means for use in a magnetic tape transport system employed for recording and reproducing data onto and from magnetic tape of a predetermined width, said air distributor means comprising: structure having a plurality of passageways arranged in at least one array along a predetermined dimension of said structure for directing air from a flow path to a surface of the magnetic tape by way of said passageways, said passageways increasing in cross sectional area toward the edges of said tape outward from the point of greatest air pressure within said flow path.
 4. The air distributor of claim 3 wherein: said structure has a surface which is substantially parallel to the plane of said tape when supported in said tape transport system, said passageways extending in a direction perpendicular to said surface of said structure whereby air is directed through each passageway substantially perpendicular to the surface of the tape.
 5. The air distributor of claim 4 wherein: said structure has two arrays of said passageways formed therethrough and parallel to each other, said passageways of each array increasing in size outward from the point of greatest air pressure within said flow path, and said passageways of each array being formed in opposite edges of said structure. 